Consider Escalonia, evergreen, small leaf, small pink flowers, easy to clip, likes the seaside, neat, even and compact, not fussy where it grows and easy to propagate. Dip a 6 inch clipping in hormone rooting powder, pop in a 6 inch pot and stand back! No, it doesn't grow too quickly, I cut only twice a year.
Forget privet; it's not that dense. Forget conifers; they're trees not shrubs, some too fast and some too slow.